CVE-2015-9135 in Android
Summary
by MITRE
In Android before 2018-04-05 or earlier security patch level on Qualcomm Snapdragon Mobile and Snapdragon Wear MDM9625, MDM9635M, MDM9640, MDM9645, MSM8909W, SD 210/SD 212/SD 205, SD 400, SD 410/12, SD 615/16/SD 415, SD 617, SD 650/52, SD 800, SD 808, and SD 810, in a QTEE syscall handler, an untrusted pointer dereference can occur.
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Analysis
by VulDB Data Team • 01/26/2020
The vulnerability identified as CVE-2015-9135 represents a critical security flaw in Qualcomm Snapdragon mobile processors that affected Android devices released prior to the 2018-04-05 security patch level. This vulnerability specifically resides within the QTEE (Qualcomm TrustZone Execution Environment) syscall handler, which operates within the secure execution environment of these mobile chipsets. The issue manifests as an untrusted pointer dereference that occurs when processing system calls within the trusted execution environment, creating a potential pathway for privilege escalation and unauthorized access to sensitive system resources. The vulnerability affects multiple Snapdragon chipset families including MDM9625, MDM9635M, MDM9640, MDM9645, MSM8909W, and various SD series processors, indicating a widespread impact across Qualcomm's mobile platform ecosystem. This flaw directly violates the fundamental security principles of trusted execution environments where all inputs should be validated before processing.
The technical nature of this vulnerability stems from improper validation of pointers within the QTEE syscall handler implementation. When the system processes certain system calls from untrusted contexts, it fails to properly validate pointer inputs before dereferencing them, allowing an attacker with access to the system to potentially craft malicious inputs that could cause the processor to jump to arbitrary memory locations. This unvalidated pointer dereference creates a condition where attacker-controlled data can influence the execution flow of the secure environment, potentially leading to privilege escalation from user mode to kernel mode or even to the trusted execution environment itself. The vulnerability's classification aligns with CWE-476 which describes NULL pointer dereference issues, though in this case it's specifically an untrusted pointer dereference within a secure execution context. From an operational standpoint, this vulnerability represents a severe threat to device security since it operates within the Trusted Execution Environment where sensitive operations such as cryptographic key handling, secure boot processes, and biometric authentication typically occur.
The operational impact of CVE-2015-9135 extends beyond simple privilege escalation, as it can potentially compromise the entire security architecture of affected devices. Attackers could leverage this vulnerability to bypass secure boot mechanisms, extract cryptographic keys from secure storage, or gain unauthorized access to biometric data and other sensitive information protected by the TrustZone environment. The vulnerability's presence in multiple chipset families means that a significant number of Android devices were potentially at risk, particularly those manufactured between 2015 and early 2018. This vulnerability aligns with ATT&CK technique T1068 which describes exploiting vulnerabilities in legitimate programs to gain system privileges, and T1548.001 which covers abuse of system privileges through privilege escalation. The attack surface is particularly concerning because it operates at the intersection of hardware security and software execution, making it difficult to detect and mitigate through traditional software-based security measures.
Mitigation strategies for CVE-2015-9135 primarily involve applying the appropriate security patches released by Qualcomm and device manufacturers, which typically include firmware updates and kernel patches to properly validate pointer inputs within the QTEE syscall handler. Organizations should ensure that all affected devices receive the 2018-04-05 security patch or later, as this specific vulnerability was addressed through proper input validation mechanisms. Device manufacturers should implement robust firmware update mechanisms to ensure timely deployment of security patches across their device fleets. Additionally, network administrators should monitor for potential exploitation attempts and consider implementing network-based intrusion detection systems to identify suspicious activities that might indicate exploitation attempts. The vulnerability serves as a reminder of the critical importance of secure coding practices in trusted execution environments and highlights the need for comprehensive security testing of system call handlers that operate within secure contexts. Security teams should also consider implementing device monitoring solutions that can detect anomalous behavior patterns consistent with privilege escalation attempts and maintain detailed audit logs of system call activities within the trusted execution environment.